Appropriate Tests


Eosinophilia can be caused by a number of conditions (see below). Evaluation of the patient’s medical history and clinical presentation and findings is required to determine the appropriate tests and underlying cause.

Review clinical findings; follow up Full blood count, White cell count differential, Blood film.

See Table 4.

Drug hypersensitivity

Correlate with drug history.

Atopic disease
  • Eczema
  • Asthma
  • Food allergy


See Food intolerance/allergy.

Skin disorders

  • Psoriasis
  • Scabies

Skin biopsy with IH, if indicated.

Eosinophilic granuloma


Parasitic infection (with tissue invasion)

  • Toxocara sp
  • Ascaris
  • Strongyloides stercoralis
  • Schistosomiasis
  • Trichinella, Filariasis
  • Cysticercosis
  • Echinococcus

Ova cysts parasites faeces.

Toxocara Ab.

Strongyloides sp Ab on clotted blood, Harada culture - consult the pathologist. This is important to identify in patients on steroids or immunosuppression, who have lived in tropical countries, since they are at risk of hyperinfection syndrome.

Antibody or PCR (molecular) tests may be available for the parasites listed and others. Check the correct sample type, timing of collection and sample volume with the laboratory.

Neoplastic diseases

Haematological neoplasms:

  • Myeloproliferative neoplasms (MPN) with eosinophilia and abnormalities of PDGFRA, PDGRFB OR FGFR1
  • Chronic eosinophilic leukaemia
  • Systemic mastocytosis
  • Other MPNs
  • Lymphoid neoplasms (eg, B-cell lymphoma, ALL, Sezary syndrome)

Non-haematological neoplasms

Bone marrow biopsy, aspirate and trephine, Flow cytometry, Cytogenetics - oncology and molecular studies as directed by morphology.

Idiopathic hypereosinophilic syndrome (HES)

Defined as a marked eosinophilia (> 1.5 x 109/L) for more than 6 months, for which no cause can be found and which is associated with signs of organ involvement and dysfunction and no evidence of eosinophil clonality.

It is a diagnosis of exclusion.

Biopsy of appropriate tissue, if indicated.

Loeffler’s syndrome

Stool sample to be examined for parasites, especially Ascaris.

Eosinophilic leukaemia

Bone marrow biopsy (bone marrow aspiration and trephine).

Pulmonary infiltration with eosinophilia (PIE) including

  • Allergic bronchopulmonary aspergillosis
  • Cocaine pneumonitis

Skin prick allergen testing especially antigens of Aspergillus sp. Aspergillus precipitins. Allergen specific Immunoglobulin E. See under Aspergillosis.

Vasculitis, especially

  • Churg-Strauss syndrome




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